Ill-fitting shoes can lead to pain, discomfort and a variety of foot illnesses, including inflammatory sores and blisters, hard corns, ingrown nails, calluses and impinged nerves in the foot. Diabetic patients may not feel pain or discomfort when a shoe is tight, and therefore a good fitting is particularly important to avoid foot illnesses.
Feet may sometimes be classified into three categories: Ectomorph (i.e., tall, slender, long-boned and slim), Mesomorph (i.e., stocky, muscular, heavy-boned) and muscled Endomorph (i.e., fleshy, plump, small-boned and fatty). Yet no particular physique entirely matches any one of these categories. Rather, most feet are a combination of the three categories, with one type being dominant. Thus, it is practically impossible to define a “normal foot.”
In 1982 the national Prescription Footwear Association completed the measurement of 6,800 pairs of adult men and women's feet in 23 cities. Not a single perfectly matched pair was found. Most people have one foot larger than the other. Two shoes of the same length size and width, from different shoe lasts, do not have the same interior shape, and do not fit a given customer foot equally well. A customer, even a customer who is not an orthopedic patient, may have a foot that is the same length and width as a given shoe, but the shoe may nevertheless not provide a good fit.
Known shoe fitting methods tend to describe feet in terms of length, and possibly also width, generally a ball width. Yet, as will be shown in FIG. 1, the foot outline 10 is a complex shape, which cannot be adequately described by any two dimensions. Indeed, a large plurality of points needs to be considered, essentially forming a complete outline of the foot.
A shoe last is a mold over which the shoe is made. The shoe last gives the shoe its shape. Different shoe patterns, sizes and widths are derived from the shoe last. Hence, the shoe-last shape determines the fit and feel of the shoe on a specific foot. Shoes are often provided with interchangeable insoles (referred to herein as an insole adapters, or adapters for brevity when there are more than the standard pair comes with the shoe), which follow the outline of the bottom of the shoe last.
The last bottom outline is the outline derived from the template cut from the bottom side of the shoe last, i.e., the part that interfaces with the insole, and depends on the shoe size, width, and design. The insole pattern substantially follows the last-bottom outline.
The methods and systems described herein refer to shoes having interchangeable insole adapters. The standard insoles provided with the shoes define different inner volumes according to the shoe last.
It is important to note that shoes having the same length and width sizes but different designs may have different shapes, hence different last-bottom outlines, or insole patterns. The weight-bearing area provided by the outline of the last-bottom outline has an important influence on comfort.
Another parameter to consider is the shoe girth, as illustrated in FIG. 2A. For a given shoe last 16, the shoe girth is the shoe cross-section at a given location, for example, along the ball width 16A, or along a waist width 16B, or along an instep girth 16C. For the given shoe last 16, and at that location, the girth determines the shoe volume.
Moreover, it is known that shoe sizes are not always consistent. Hence, even the most exacting foot measuring of length and width is still confronted with the problem of the inconsistency of shoes size, width and shapes.
The foregoing issues have been addressed by several patents and patent applications, for example U.S. Patent Application Publications 2004/0148804, 2005/0049816, 2002/0157266 and 2005/0028109, and U.S. Pat. Nos. 6,331,893, 6,741,728, 6,735,547 and 6,289,107, whose disclosures are incorporated herein by reference.
As another example, in a press release dated Jan. 17, 2006 (after the priority date of the present patent application), the Timberland Company (Stratham, N.H.) announced a fitting system called PreciseFit™, in which each box of shoes is supplied with a set of inserts of varying thicknesses that lock on to a removable footbed.